The present invention pertains to optical scanning devices, such as document scanners. We will use the expression “document scanner” or “scanner” to refer to such devices, although it is understood that objects other than documents can be scanned with such devices. For example, one side of a three dimensional object, such as a sculpture, can frequently be scanned by an optical scanning device. Further, the scanner can be a separate device used to scan documents and the like, or it can be a component of an imaging device such as a photocopier or a facsimile machine. Further, the optical scanner can be a component in a multi-function printer, which can perform two or more different functions (such as printing a document, sending and receiving facsimiles, producing photocopies, and scanning a document). The scanner can be used as a component in a digital imaging device, or an analog imaging device. Accordingly, the expression “document scanner” as used herein should not be considered as meaning only a stand-alone document scanning apparatus, but any optical scanning system used as part of an image processing device.
Optical document scanners are well known in the art, and are frequently used to scan a document containing text and, or, images such as photographs. The object to be scanned is typically positioned on the top side of a transparent (typically glass) platen. One or more scanning light bars are then moved over the bottom side of the platen, and light from the light bar is reflected by the object being scanned to a series of sensors, or to an optical photoconductor. Since dark areas of the object will normally reflect less light than light colored areas of the object, the sensors can record the light and dark patterns of the object. The data from the sensors can be stored as a digital file, thereby producing an electronic, digital “copy” of the side of the object which has been scanned by the optical scanner. In the case wherein the light is reflected to an optical photoconductor (“OPC”), a toner material can then be used to transfer a copy of the scanned image from the OPC to a sheet of media such as paper. In a color scanning process, the light bar(s) may be scanned over the image a number of times to record light reflected from the object at different wavelengths. Further, in some imaging devices (a facsimile machine, for example) the light source remains stationary while the document is moved past the light source by a series of powered rollers.
Typically, a user can use an applications program to view and edit the digital file of the scanned object. The applications program (“software”) allows the digital file to be visually presented to the user on a computer monitor or the like. A number of different operations can typically be performed on the file via the applications program to enhance the file's value to the user. For example, the user can edit or “crop” the scanned image as displayed on the monitor to thereby delete unwanted or unnecessary parts of the scanned image which the user does not need. For example, a user may wish to scan a portion of the page of a newspaper to thereby acquire a digital copy of an article of interest to the user. The text and images in articles and advertisements surrounding the article of interest may be of no interest to the user. Accordingly, the user will normally lay the portion of the newspaper containing the article of interest on the platen of the scanner and will then press a button to begin the scanning process. The scanner will scan not only the article of interest, but any collateral material which is also present on the scanner platen. The user can afterwards use the scanner applications program to delete the unwanted parts of the scanned image.
This prior art method of allowing a user to acquire a selected portion of an overall scanned image has some problems. For example, when an applications program is used, the entire file of the scanned image must be processed, consuming valuable computer resources and increasing the length of time required for the editing process. Further, if the document was not carefully laid on the scanner platen in a preferred orientation prior to the scanning process, the scanned image may need to be manipulated (rotated, for example) to allow the cropping process to crop only the undesired portion of the scanned image. As can also be appreciated, unless an applications program is available to manipulate a digital image or the scanned object, or a copy of the scanned image is generated, then the user may not even know if the desired area of interest was scanned or not. This situation can arise for example when a user desired to send a facsimile containing only a portion of a document.
As an alternative to using an applications program to crop the scanned image the user can block out the unwanted portions of the original document prior to scanning the document, as for example by applying paper over the unwanted portions. Another alternative is for the user to cut the desired portion out of the original manuscript and thus scan only the portion of interest. These alternatives have obvious drawbacks. Firstly, blocking out unwanted portions of the document takes time, may not effectively block the unwanted portions, and may also damage the original document if tape or the like is used to hold the blocking material in place. The alternative, i.e, cutting the desired portion out of the original document, may not be a viable option in many cases, as it will damage the original document. An alternative to cutting the original manuscript is to make a full copy of the original manuscript (such as a page of a book), and then to cut the desired portion out of the copy. The desired portion of the copy can then be scanned separately. However, this requires extra steps on the part of the user, and also the final resulting image generated by the scanning device may be noticeably degraded from the original document as a result of using intermediate copies to arrive at the final result.
In addition to the problems of editing the scanned image to acquire only the desired portion of the overall scanned image, the process of scanning can be a relatively slow process at high resolutions. Thus, a user may desire to only scan one-fourth of the overall scanable area of a document. However, the scanning process is performed over the entire scanable area, thus requiring more scanning time than is required to scan only the portion of interest.
A couple of related problems pertain to the scanning process used in photocopiers and the like. The first problem arises when a document comprising a sheet of paper larger than the scanable area is placed on the platen of a photocopier or a scanner. Since the document is typically placed in a face-down position on the platen, the user normally will not know with certainty what area of the document will be scanned or copied. The user may have to make a number of copies (or perform a number of scans) of the document, repositioning the document each time, until the desired area is copied or scanned. The second problem pertains to making an enlargement of a portion of a document placed on the platen of a photocopier or a scanner. In this case the user typically is required to do some “guess-work” to estimate whether or not the portion of the document desired to be enlarged will in fact be the portion of the document scanned by the scanner. Again, the user may need to make a number of copies or scans until the desired enlargement is generated.
What is needed then is an optical scanner which achieves the benefits to be derived from similar prior art devices, but which avoids the shortcomings and detriments individually associated therewith.